Objective To observe the effects of the lactose content in feed, the time duration of chronic restraint stress and the duration of modeling on the diarrhea?predominant of irritable bowel syndrome (IBS?D) model rats, and to select a preferred method for establishing the IBS?D rat model. Methods Rats were randomly divided into a normal control group, model group A (30% lactose + bound for 1 h), model group B (30% lactose + bound for 1.5 h), model group C (45% lactose + bound for 0.5 h), and model group D (45% lactose + bound for 1 h). The visceral sensitivity was evaluated with the pain threshold at the time of abdominal wall retraction on the 7th, 10th, and 14th days after modeling. The diarrhea index was used to evaluate the extent of diarrhea. A multi?channel physiological signal acquisition processing system was used to record the wave in jejunum smooth muscle movement at 1 h after feeding. Wave amplitude, frequency analysis, and movement calculation were used to evaluate gastrointestinal dynamics. Results The capacity threshold in each model rat at 7, 10, and 14 days was significantly lower than that in the normal control group. Diarrhea indexes at 7, 10, and 14 days were obviously increased compared with the normal control group. Model group D had less significant abnormalities in rhythmic movement of smooth muscle. Conclusions When lactose in the feed is > 30% with a time duration of chronic restraint stress for more than 1 h, gastrointestinal motility abnormalities and visceral high sensitive state of typical IBS?D occur in the model rats at 7 -14 days after modeling.